title: Problems in methods for the detection of significant proteinuria in pregnancy.
abstract: OBJECTIVE
  The aim of this study was to underscore problems associated with the dipstick test and determination of protein concentration alone in spot-urine (P-test) compared with spot-urine protein-to-creatinine ratio (P/Cr test) and to determine whether urine collection for 24-h test was complete.
  
  
  METHODS
  Dipstick and P/Cr tests were performed simultaneously in 357 random spot-urine specimens from 145 pregnant women, including 35 with pre-eclampsia. Positive results were defined as ≥ 1+ on dipstick test, protein concentration ≥ 30 mg/dL on P-test, and P/Cr ratio ≥ 0.27 (mg/mg) on P/Cr test. Sixty-four 24-h urine tests (quantification of protein in urine collected during 24 h) were performed in 27 of the 145 women. We assumed that P/Cr ratio ≥ 0.27 predicted significant proteinuria (urinary protein ≥ 0.3 g/day). The 24-h urine collection was considered incomplete when urinary creatinine excretion was <11.0 mg/kg/day or >25.0 mg/kg/day.
  
  
  RESULTS
  Forty-four percent (69/156) of specimens with a positive test result on dipstick test contained protein < 30 mg/dL. Dipstick test was positive for 25.7% (69/269) of specimens with protein < 30 mg/dL and for 28.8% (79/274) of specimens with P/Cr ratio < 0.27. P-test results were positive for 7.3% (20/274) and negative for 18.1% (15/83) of specimens with P/Cr ratio < 0.27 and ≥ 0.27, respectively. Incomplete 24-h urine collection occurred in 15.6% (10/64) of 24-h urine tests. Daily urinary creatinine excretion was 702-1397 mg, while creatinine concentration varied from 16 mg/dL to 475 mg/dL in spot-urine specimens.
  
  
  CONCLUSIONS
  Dipstick test and P-test were likely to over- and underestimate risks of significant proteinuria, respectively. The 24-h urine collection was often incomplete.
authors.affiliation: Department of Obstetrics, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Yamada
authors.forename: Takashi
authors.initials: T
authors.lastname: Kojima
authors.forename: Rina
authors.initials: R
authors.lastname: Akaishi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ishikawa
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Takeda
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kawaguchi
authors.forename: Ryutaro
authors.initials: R
authors.lastname: Nishida
authors.forename: Mamoru
authors.initials: M
authors.lastname: Morikawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamada
authors.forename: Hisanori
authors.initials: H
authors.lastname: Minakami
mesh_terms: D000328:Adult; D000465:Algorithms; D003404:Creatinine / Q000652:urine; D005260:Female; D006801:Humans; D007564:Japan; D010349:Patient Compliance; D011225:Pre-Eclampsia / Q000175:diagnosis* / Q000503:physiopathology / Q000652:urine; D011237:Predictive Value of Tests; D011247:Pregnancy; D011506:Proteins / Q000032:analysis; D011507:Proteinuria / Q000209:etiology*; D011934:Reagent Strips; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index
chemical_list: D011506:Proteins; D011934:Reagent Strips; D003404:Creatinine
keywords: creatinine in the urine; protein-to-creatinine ratio; proteinuria